Revert "Fix the supervisord web template, to avoid the kombu crash bug. Document the problem. Add a test to be sure `gunicorn` is present in INSTALLED_APPS."
It didn't fix the kombu crash (which is caused by celery tasks encoding problem), and generates transient "address already in use, retrying…" errors in sentry, which is IMO worse than before.

This reverts commit d809f7f3f3b0859b69bf1506b741a179088eec80.
bump version in setup.py
Merge branch 'release/2.4.4'
Merge tag 'sparks-2.4.4' into develop

2.4.4